Two-part metallic mine prop



Feb. 28, 1961 w. L. G. HEUSNER I 2,973,178

TWO-PART METALLIC MINE PROP Filed Oct. 24, 1957 prop member fixedly connected thereto.

'mine prop members-are locked to-each other.

United States Patent C TWO-PART lVLETALLIC MINE PROP Williehn Ludwig Gustav Heusner, Bochum-Weitmar, Ger- .many, assignor to Hermann Schwarz K.G., Wattenscheid, Germany Filed Oct. 24, 1957, Ser. No. 692,208

Claims priority, application Germany Oct. 29, 1956 '4 Claims. (Cl. 248-354) The present invention relates to a two-part metallic mine prop in which the mine prop members are locked 2,973,178 Patented Feb. 28, 1961 member 11 and is fixedly connected thereto. The pressure cylinder may be formed by the inner wall of the tubular upper mine prop member 11. In such an instance, the upper mine prop member must not only have 5 a wall thickness necessary to withstand the considerable improved mine prop of the above type which can be particularly quickly set and robbed.

It is another object of this invention to provide a twopart metallic mine prop which can be quickly set by the employment of fluid operable means.

,These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the attached drawing illus- According to the invention, one of the two mine prop members has mounted therein apressure cylinder fixedly :connected thereto. The said pressure cylinder cooperates with a-piston relatively movable thereto. The mine prop member comprising said pressure cylinder has an opening for connection with a pressure fluid adapted to bring about the setting of the mine prop. The pressure cylinder'may form the inner wall 'of the tubular mine It is also possible to mount a separate pressure fluid cylinder in the hollow mine prop and fixedly to connect said pressure cylinder to .the hollow mine prop member. A mine prop according to the invention may be set by filling the pressure fluid cylinder with the pressure fluid and, after the mine prop has been placed under setting load, the

Thereupon, the pressure fluid is released and is, at least to a majorextent, withdrawn from the mine prop. When robbingthe mine prop, the friction lock only of the locked mine prop member has to be released. The mine prop may be setparticularly quickly when the pressure fluid is employed and made effective in two stages, namely in afirst stage in which the cylinder is filled and the .upper mine prop member is lifted at low pressure up mounted thereon a clamping ring 12 which is tightened vby .driving in a wedge 13.

A simple and sturdy construction for the mine prop according to the. invention is obtained when the pressure cylinder is arranged within the tubular upper mine prop the beam 16 carrying the overburden 17, is provided forces of the overburden to be absorbed by the mine prop but must also have a suflicient smooth inner surface so that the piston 21 reciprocable therein can slide properly therein. The shape of the inner surface must very precisely correspond to that of a cylinder in orderto assure a tight sealing for the pressure fluid by means of the cylinder wall and the piston.

If the upper mine prop member consists of a drawn steel pipe, its inner surface must be post-machined because drawing itself cannot yield a sufliciently precise inner diameter of the steel pipe.

According to a further development of the invention, a light metal tube for instance of aluminum may be inserted into the steel upper mine prop member 11 and may be connected thereto in any convenient manner so that the. light metal tube forms the pressure cylinder.

When producing light metal tubes by drawing, it is possible whenemploying a mandrel or a ball to maintain a precise inner diameter within close tolerances and also to obtain a proper circular cross section. The inner surface obtained by drawing in this way will have the required smoothness and will be able without requiring post-machining satisfactorily to seal the pressure cylinder in cooperation with a sealing sleeve mounted on the piston.

i The employment of light metal has the advantage that also when employing water or water containing pressure fluid, no corrosion will occur.

As will be seen from the drawing, the head 15 of the upper mine prop member which is mounted below with an'outlet'bore 18. This bore 18 is normally closed with regard to the pressure chamber 20, by means of a spring-loaded breather valve 19. This breather valve opens when the pressure in the pressure chamber drops below atmospheric pressure and makes it possible immediately to remove the pressure fluid conveyed into the mine prop for setting the same. When handling the mine prop, the pressure fluid is not contained therein so that it does not increase the weight of the mine prop during its transportation or mounting.

As will be seen from the drawing, the cylinder 14 confines a piston 21 which latter is mounted on a tube 22. The cylinder 14 and piston 21 are telescopically slidable relative to each other. The tube 22 is preferably coaxially arranged in the hollow lower mine prop member 10. The bottom of the tube 22 has a semispherical shape and is journalled in a correspondingly shaped portion 24 of the foot of the mine prop member 25 so that the tube is journalled in the manner of a Cardan joint. The lower end of the tube 22 has connected thereto a connecting pipe 26 adapted selectively to be closed by a cap 27. When the cap 27 is removed, a hose 28 may be connected with the pipe 26 in a pressure tight manner. 7

Instead of providing the connection for the pressure fluid at the bottom portion of the tube 22, such connection may also be provided onthe pressure cylinder 14. Thesupply and withdrawal of the pressure fluid may be effected for instance by a piston pump. 'The pressure 'erated motor. Such pump must be so designed that in its second stage it will produce the required setting pressure.

The arrangementshown in the drawing furthermore comprises an air control valve 29 which is connected through a hose 30 with a compressed air container (not shown). Valve 29' has a control lever 31 adapted to be moved into any of four diflerent positions 32 to 35-. Position 32 of the lever 31 represents the zero or neutral position in which the hose 30 is closed off, in other words, in which .no air is conveyed through the valve. Position 33 represents the filling position. Position 34 represents the pressing position, whereas position 35 represents the release position.

A particularly simple arrangement for supplying a hydraulic fluid is obtained when employinga hydraulic fluid container the upper surface of which is adapted to be subjected to the influence of air under pressure. Such container works in the manner of the well known tandem pumps (Vorortspumpen) operable by compressed air. After the container has been connected to the pressure cylinder of the mine prop, the fluid is quickly pressed into said pressure chamber (first stage) and only then a smaller pump driven manually or by a motor is made effective (second stage), which produces the pressure required for setting the mine prop. When the mine prop has been locked, the fluid returns to the :container which now is under no pressure of compressed air. As far as the return of the fluid does not follow the natural drop in pressure, it is drawn back into said container by means of a pump.

According to the showing in the drawing, such fluid container is represented by the oil container 37. When the lever of the air control valve 29 occupies the position 33, compressed air is pressed through the pressure conduit 36 into the oilcontainer 37. As a result thereof, oil is conveyed from the oil container or reservoir 37 through check valve 38 and hose 28 into the mine prop. The upper mine prop member 11 is then lifted up until it engages the beam 16. When the lever 31 of the control valve 29' occupies the position 34, air passes through conduit 39 and a control valve 60 into the air cylinder 40 of a piston pump comprising the piston 4-1 the movement of which in either direction is controlled by the valve 60. Thus, the piston 41 is actuated and draws oil from the oil container or reservoir 37 through conduit 42, reversing valve 43 and conduit 44 into the high pressure cylinder 45 and presses the oil through conduit 46, reversing valve 43 and conduit 47 as well as pipe 28-into the mine prop while producing a high pressure.

After the necessary setting pressure has been obtained, the clamping ring 12 is tightened by the wedge 13 whereby the upper mine prop member 11 is locked to the lower mine prop member 10. When the control lever 31 occupies the position 35, compressed air passes through conduit 49 into the cylinder 61 where it acts upon the piston 53 which in its turn is connected to a valve spool not shown of the reversing valve 43 so as to adjust the same. The piston pump 41 then draws oil from the mine prop through hose 28, conduit 47, reversing valve 43 and conduit 50 into the oil cylinder 51 and presses the oil at low pressure through conduit 52, reversing valve 43 and conduit'42 into the oil reservoir 37, the conduit 46 of which was vented by shifting the control 'lever 31 into the position 35. When a low pressure occurs in chamber 20, valve 19 opens. The hose 28 is then removed from the mine prop. The mine prop whichis now in operative position, will then not contain any pressure fluid.

When taking advantage of a compressed air installatiOn *which as a rule is always available in mining opphere above atmospheric pressure, it is possible by means of an oil pump to carry out a two step operation in such -erations and-has a usual pressure of from 5 to 6 atmosa way "that first the cylinder is filled with compressed air by connection with a compressed air conduit. As a result thereof, the upper mine prop member is lifted. Thereupon oil is pressed into the mine prop by means of an oil pump whereby the air is further compressed and a pressure is created in the cylinder in conformity with the pressure required for the respective setting load. After the mine prop members have been locked to each other, the cylinder is connected to an oil container or reservoir so that the enclosed air will press out the oil.

A single stage method in which only oil under high pressure will be employed, may be carried out in the following manner. A high pressure conduit for oil and an oil withdrawing conduit extend through the entire mine prop. The pump for producing the oil pressure and the suction pump are mounted in the portion of the shaft in which the mining has to be carried out. Both conduits are equipped with a suflicient number of closable connections. Two hose sections each of which may be connected to oneof the two conduits, lead through a three-way valve into a further hose section which is brought into communication with the cylinder chamber of the mine prop. First the three-way valve is placed into such a position that the cylinder chamber of the mine prop is connected to the high pressure oil conduit. When the mine prop has absorbed the necessary setting load, the

struction shown in the drawing but also comprises any modification within the scope of the appended claims.

. What I claim is:

1. In a two-part metallic mine prop having an upper mine prop member, a lower mine prop member, and locking means for frictionally interlocking said mine prop members, the combination of: a pressure fluid cylinder confined by one of said mine prop members and forming a rigid unit therewith, a hollow piston extending into said cylinder, said cylinder being movable relative to said piston, a tubular piston rod connected to said piston and being open at that end thereof which is connected to said piston for selectively feeding fluid into and withdrawing fluid from said cylinder, said piston being provided with connecting means for connection with a pressure fluid system, means for preventing any substantial movement of said piston rod in axial direction thereof, conduit means associated with said cylinder and adapted to establish fluid communication between the upper portion of said cylinder and the atmosphere, and breather valve means arranged in said conduit means and operable in response to a sub-atmospheric pressure in said cylinder to establish communication between the latter and the atmosphere through said conduit means.

2. In a two-part metallic mine prop having an upper mine prop member, a lower mine prop member, and locking means for frictionally interlocking said mine prop members, the combination of: a pressure fluid cylinder confined by one of said mine prop members and forming a rigid unit therewith, a hollow piston extending into said cylinder, said cylinder being movable relative to said piston, a tubular piston rod connected to said piston and being open at that end thereof which is connected to said piston for selectively feeding fluid into and withdrawing fluid from said cylinder, said piston being provided with connecting means for connection with a pressure fluid system, the other end of said piston rod being closed and provided with a spherical bearing surface to allow adjustment of said piston rod relative to said cylinder for preventing jamming of said piston in case of a slight tilting movement of said prop members relative to each other, means for preventing any substantial movement of said piston rod in axial direction thereof, conduit means associated with said cylinder and adapted to establish fluid communication between the upper portion of said cylinder and the atmosphere, and breather valve means arranged in said conduit means and operable in response to a subatmospheric pressure in said cylinder to establish com munication between the latter and the atmosphere through said conduit means.

3. A method of setting a two-part load supporting mine prop having an upper mine prop member with a cylinder and a lower mine prop member with a stationary piston supported thereby and extending into said cylinder, which comprises the steps of: introducing air under pressure into said cylinder to thereby move said upper mine prop member into engagement with the load to be sustained, subsequently introducing oil under pressure into said cylinder to thereby place said upper mine prop member under pressure for sustaining the load to be supported while simultaneously compressing the air in said cylinder, mechanically locking said mine prop members in their relative load sustaining position, and subsequently releasing at least the major portion of said oil from said cylinder by permitting the compressed air in said cylinder to aid in expelling the oil from said cylinder.

4. A method according to claim 3, which includes the step of subjecting the oil in said cylinder during the filling thereof to high pressure, and subjecting the oil in said cylinder to sub-atmospheric pressure during the withdrawal of said oil from said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 2,200,392 Goldberg May 4, 1940 2,461,810 Curtis Feb. 15, 1949 2,474,464 Cable June 28, 1949 2,691,503 Bigelow Oct. 12, 1954 2,807,438 Frank Sept. 24, 1957 FOREIGN PATENTS 745,418 Great Britain Feb. 22, 1956 943,825 Germany June 1, 1956 986,331 France July 30, 1951 1,088,438 France Mar. 7, 1955 

